Fix slack notifications not displaying properly
#167
Use text fallback field in all places where attachments and blocks are used. Replace attachments with blocks in some cases so text is not repeated in both.
Blocks do not support having the colored line on the left. Alternatively we could use a colored dot emoji.
From slack docs:
Any content displayed within attachments may be wrapped, truncated, or hidden behind a "show more" style option by Slack clients. This isn't the case with the top-level blocks field.
Added block or text field to each postMessage and update
I tested the most recent set of changes on Ubuntu and Android. All the messages displayed properly when displaying as notifications or mentions & reactions.
@mderynck could you please provide screenshots of how Slack messages look after update?
Current (Android Mentions & Reactions) - I think the slack client was updated so they appear blank instead of "Content cannot be displayed"

Current (Android Thread)

After (Android Mentions & Reactions) - Ignore the bot icon, mine is customized so I can tell different versions apart

After (Android Thread)

Merging